Paper forming device of a paper-making machine

ABSTRACT

A paper forming device of a paper machine enables a change-over between a thin paper high velocity forming and a thick paper forming. In the paper forming device, stock liquor S is discharged from a headbox  1  onto a wire  2  and, while being transferred on the wire  2,  is dewatered by a dewatering equipment and further by a suction box  6.  A forming roll  13 , wound with an extended felt  7,  is arranged movably up and down above the wire  2  near the headbox  1.  When a thin paper is to be formed, the forming roll  13  is moved down so that a nip of the stock liquor is formed between the wire  2  and the felt  7.  Thereby, the stock liquor S discharged from the headbox  1,  can be comparatively immediately nipped between the wire  2  and the felt  7.

TECHNICAL FIELD

[0001] The present invention relates to a paper forming device of apaper machine in which stock liquor is discharged from a headbox onto awire to be dewatered, while being transferred on the wire, by adewatering equipment and to be further dewatered by a suction box.

BACKGROUND ART

[0002]FIG. 3 shows a prior art example of a paper forming device inwhich stock liquor of paper is discharged from a headbox onto a formingwire to be dewatered, while being transferred on the wire, for forming awet sheet.

[0003] In FIG. 3, numeral 1 designates a headbox that discharges stockliquor and numeral 2 designates a wire. The wire 2 is made in an endlessloop form, as seen in FIG. 3, and has its upper surface portion formedas a horizontal run portion (Fourdrinier table portion) 3 for formingthe wet sheet.

[0004] Below the wire 2 forming the horizontal run portion 3, in theorder from the headbox 1 on the left hand side to the right hand side, aforming board 4, a dewatering equipment 5 and a suction box 6 arearranged.

[0005] Above the suction box 6, provided is a felt 7 that is constructedbeing belted between a felt roll 8 and a pick-up roll 9 so as to runwith the wire 2 sandwiched between the felt 7 and an upper surface ofthe suction box 6.

[0006] Numeral 10 designates a frame and numeral 11 designates asave-all that is provided on the frame 10 for receiving water dewateredof the stock liquor on the wire 2. Numeral 12 designates a breast rollthat is provided below the headbox 1 for guiding the wire 2.

[0007] In the paper forming device shown in FIG. 3 having theconstruction as mentioned above, stock liquor S is discharged from theheadbox 1 onto the forming board 4 portion of the horizontal run portion3 of the wire 2. While being transferred on the wire 2, the stock liquoris dewatered by the dewatering equipment 5. As the stock is beingtransferred on the wire 2, it reaches on the suction box 6 and is nippedbetween the wire 2 and the felt 7. Thus, by a vacuum force actingthrough the suction box 6 and by a compression force acting due totension of the felt 7, dewatering is further carried out, so that a wetsheet mat M is formed.

[0008] Then, the wet sheet mat M formed on the wire 2, together with thefelt 7, is transferred to a press part (not shown) as the next step bythe pick-up roll 9.

[0009] The prior art paper forming device described above has acomparatively large length of the horizontal run portion 3 and thus, incase of forming a thin paper at a high velocity of 850 m/minute or more,scattering or the like of the stock liquor, while being transferred onthe wire 2, is caused, so that there arises a problem that uniformity ofthe paper forming is obstructed and operation of the machine becomesdifficult.

[0010] In view of the abovementioned problem of the paper forming devicein the prior art paper machine, it is an object of the present inventionto provide a paper forming device of a paper machine that has astructure enabling to perform a change-over between a thin paper highvelocity forming and a thick paper forming.

DISCLOSURE OF THE INVENTION

[0011] In order to solve the abovementioned problem in the prior art,the present invention provides a paper forming device of a paper machinein which stock liquor is discharged from a headbox onto a wire so thatthe stock liquor, while being transferred on the wire, is dewatered by adewatering equipment and is further dewatered by a suction box,characterized in being constructed such that a forming roll, wound witha felt, is arranged movably up and down above the wire near the headboxand, when a thin paper is to be formed, the forming roll is moved downso that a nip of the stock liquor is formed between the wire and thefelt.

[0012] According to the paper forming device of the present inventionconstructed as mentioned above, when a thin paper of 35 g/m² or less,for example, is to be formed, the forming roll is moved down to therebypress down the wire. In this state, forming of a wet sheet is done. Inthis state, the stock liquor discharged from the headbox onto the wireis immediately nipped between the wire and the felt to receive acentrifugal force and a compression force due to the tension of thewire. Hence, the most part of the water in the stock liquor is dewateredand the wet sheet is rapidly formed.

[0013] On the other hand, when a thick paper of 35 g/m² or more, forexample, is to be formed, the forming roll is moved up and a wet sheetis formed by the same construction as the prior art device shown in FIG.3.

[0014] Thus, according to the paper forming device of the presentinvention, when a thin paper is to be formed, by moving down the formingroll, the stock liquor discharged from the headbox is immediately nippedbetween the wire and the felt. Thereby, forming of the wet sheet can bedone with the open portion being shortened, scattering or the like ofthe stock liquor on the wire is suppressed and a high velocity formingof the thin paper becomes possible.

[0015] Also, according to the paper forming device of the presentinvention, when the thin paper is to be formed, the stock liquordischarged from the headbox is immediately nipped between the wire andthe felt wound around the forming roll, so that a shear force isgenerated in the stock liquor and fibers are oriented in the runningdirection of the wire. Thereby, a soft thin paper can be easily formed.

[0016] Thus, according to the device of the present invention, not onlyforming of a thick paper but also a high velocity forming of a thinpaper become possible.

[0017] In the paper forming device of the present invention, while thewire is pressed down by the forming roll and a running direction of thewire changes, such a construction that, when the forming roll is moveddown to thereby press down the wire, the headbox and the forming boardarranged under the wire are inclined in the same direction as therunning direction of the wire so pressed down is preferably employed.Thus, the position relation between the wire running direction and theheadbox and/or the forming board can be maintained.

[0018] Also, the paper forming device of the present invention can beconstructed such that a wire roll is arranged upwardly movably under thewire downstream of the forming roll and, when the wire roll is moved upto thereby lift up the wire, the forming roll is moved down so that ahorizontal running direction of the wire near the headbox is maintained.Thus, even when the forming roll is moved down, the horizontal runningdirection of the wire between a breast roll and the forming roll can bemaintained and, in forming not only a thick paper but also a thin paper,displacement of the headbox and the forming board becomes unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a side view showing a construction of a paper formingdevice of a first embodiment according to the present invention.

[0020]FIG. 2 is a side view showing a construction of a paper formingdevice of a second embodiment according to the present invention.

[0021]FIG. 3 is a side view showing a construction of a prior art paperforming device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Herebelow, the paper forming device of the present invention willbe described more concretely based on embodiments according to thepresent invention as shown in FIGS. 1 and 2. It is to be noted that, inFIGS. 1 and 2, the same parts and components as those shown in FIG. 3are denoted with the same reference numerals as in FIG. 3 and repeateddescription thereon will be omitted.

First Embodiment

[0023] The paper forming device of a first embodiment shown in FIG. 1will be first described.

[0024] In FIG. 1, numeral 13 designates a forming roll that is arrangedmovably up and down above the wire 2 near the headbox 1. The felt 7 iselongated beyond the length of the prior art felt that extends on thesuction box 6, so that the felt 7 is belted between the forming roll 13and the pick-up roll 9. The forming roll 13 is constructed so as to besupported either in a lower position A or in an upper position B in FIG.1 by an appropriate mechanism that is not shown. Numeral 14 designates acurved blade that is formed having a curvature on a surface of No. 1blade. The No. 1 blade is a blade of the first one of two units of thedewatering equipment 5.

[0025] Also, in the paper forming device shown in FIG. 1, the headbox 1and the forming board 4 are respectively constructed to be inclinedlymovable from the horizontal positions shown by dotted lines to theinclined positions shown by solid lines. As the mechanism to support theheadbox 1 and the forming board 4 in their horizontal positions andinclined positions may be appropriately selected from the known art,detailed construction thereof is not shown.

[0026] Other portions of the structure of the paper forming device shownin FIG. 1 are substantially the same as those portions of the deviceshown in FIG. 3 and, by denoting them with the same reference numerals,description thereon is omitted.

[0027] In the paper forming device of the first embodiment of FIG. 1constructed as mentioned above, when a thin paper of 35 g/m² or less,for example, is to be formed, the forming roll 13 is moved down to thelower position A, as shown by solid lines, so that the felt 7 and thewire 2 in this position are pressed down by the forming roll 13.

[0028] Thereby, the stock liquor S discharged from the headbox 1 isnipped comparatively immediately by and between the felt 7, that iswound around the forming roll 13, and the wire 2, and the most part ofthe water contained in the stock liquor S is dewatered by a centrifugalforce and a compression force due to the tension of the wire 2 so as toform a wet sheet.

[0029] Also, it is so constructed that, when the forming roll 13 ismoved down to thereby press down the wire 2 for forming the thin paper,both of the headbox 1 and the forming board 4 are correspondinglyinclined, as shown by solid lines in FIG. 1, so that the positionrelation between the running direction of the wire 2, so pressed down,and the headbox 1 and/or the forming board 4 is maintained in the sameway as in the structure in which all of the wire 2, the headbox 1 andthe forming board 4 are horizontally arranged.

[0030] Further, the curved blade 14 as the No. 1 blade of the first unitof the dewatering equipment 5 has its surface formed in the curvature,the wire 2, the wet sheet and the felt 7 can smoothly run on the curvedblade 1.

[0031] Thus, according to the paper forming device shown in FIG. 1, evenwhen the thin paper is formed at a high velocity, scattering or the likeof the stock liquor is suppressed and a high quality thin paper can bestably formed.

[0032] On the other hand, when a thick paper of 35 g/m² or more, forexample, is to be formed, if the forming roll 13 is kept in theabovementioned lower position, a smooth nipping of the stock liquorbecomes difficult at the nip portion between the felt 7 and the wire 2so that so-called a backflow of the stock liquor arises and a seriousdefect in the paper may be brought about. Hence, the forming roll 13 ismoved up to the upper position B, as shown by dotted lines in FIG. 1.

[0033] At the same time, the headbox 1 and the forming board 4 arearranged in the horizontal position, as shown by dotted lines in FIG. 1,so as to be in line with the running direction of the wire 2 near theheadbox 1. Thus, in case of forming the thick paper, the paper formingdevice of the first embodiment is operated as a device to form the wetsheet in the same way as the prior art paper forming device shown inFIG. 3.

[0034] As mentioned above, the paper forming device of the firstembodiment of FIG. 1 enables to stably form a high quality paper both ofa thin paper and a thick paper by a single unit of the machine.

Second Embodiment

[0035] The paper forming device of a second embodiment shown in FIG. 2will be described.

[0036] In FIG. 2, numeral 15 designates a wire roll that is arrangedunder the wire 2 between two units of the dewatering equipment 5 and isconstructed so as to be supported either in an upper position A′ shownby solid lines in FIG. 2 or in a lower position B′ shown by dottedlines. In the paper forming device of the present second embodiment, theheadbox 1 and the forming board 4 are arranged in the horizontalpositions as shown in FIG. 2 unlike the structure of the firstembodiment in which they are inclinedly movable. Other portions of thestructure of the second embodiment shown in FIG. 2 are substantially thesame as those portions of the paper forming device of the firstembodiment shown in FIG. 1 and description thereon will be omitted.

[0037] As understood by the above description, in the paper formingdevice of the second embodiment shown in FIG. 2, it is so constructedthat, when the forming roll 13 is moved down to thereby press down thefelt 7, in order to maintain the position relation between the runningdirection of the wire 2 and the headbox 1 and/or the forming board 4,neither the headbox 1 nor the forming board 4 is inclined but the wireroll 15 is moved up to thereby lift up the wire 2.

[0038] When a thin paper is to be formed by the paper forming device ofthe second embodiment of FIG. 2, the forming roll 13 is moved down toposition A, as shown by solid lines in FIG. 2, that makes contact withthe wire 2 and the wire roll 15 is moved up to the upper position A′, sothat a predetermined wire holding angle of the forming roll 13 isobtained. Thus, in the present second embodiment, even when the formingroll 13 is moved down, the horizontal position relation between thebreast roll 12 and the forming roll 13 is maintained and such aconstruction as to arrange the headbox 1 and the forming board 4inclinedly movably is not necessary.

[0039] Also, in the present second embodiment, for the reason asmentioned above, such a curved blade as that 14 provided in the paperforming device of the first embodiment of FIG. 1 is not necessary.

[0040] When a thick paper is to be formed by the paper forming device ofthe second embodiment of FIG. 2, the forming roll 13 is moved up toposition B, as shown by dotted lines in FIG. 2, and the wire roll 15 ismoved down to the lower position B′, as shown by dotted lines, that is,the wire roll 15 is moved down until the horizontal running direction ofthe wire 2 is realized. In this state, the wire roll 15 is used as atable roll. Otherwise, the wire roll 15 may be constructed so as to bepositionable slightly below the wire 2.

[0041] In the paper forming device of the present second embodiment, ascompared with the first embodiment, there is needed no such a mechanism,that requires a high mounting accuracy, to incline the headbox 1 and theforming board 4 corresponding to the inclination of the runningdirection of the wire 2. Hence, there is obtained an advantage that noloss time is caused for a position adjustment of the equipment anddevices, a change-over of the stock liquor pipings, etc.

[0042] In forming the thin paper by the device of the present secondembodiment also, stock liquor S discharged from the headbox 1 is nippedcomparatively immediately by and between the felt 7 and the wire 2 andoccurrence of scattering or the like of the stock liquor S can besuppressed even in the high velocity paper forming. Moreover, in thethin paper forming, contact of the wire 2 to the dewatering equipment 5and the suction box 6 is minimized. Thereby, the necessary drive forceof the wire is reduced and the life of the wire can be elongated.

[0043] While the invention has been described concretely based on theembodiments as illustrated, the invention is not limited to theembodiments but, as a matter of course, may be added with variousmodifications within the scope of the invention as defined by theappended claims.

[0044] For example, while the felt 7 wound around the forming roll 13has been described as the elongated one of the felt on the suction box6, the felt to be wound around the forming roll 13 may be constructed asa loop of felt that runs between other rolls independently of the felton the suction box 6.

[0045] Also, while the No. 1 blade of the first unit of the dewateringequipment 5 has been described as the curved blade 14, not necessarilythe curved blade 14, such one as enables a smooth running of the wire 2,the wet sheet and the felt 7 on the dewatering equipment may beprovided. For example, a roll may be provided immediately before thedewatering equipment instead of the curved blade 14.

[0046] INDUSTRIAL APPLICABILITY

[0047] As described above, the present invention provides a paperforming device of a paper machine in which stock liquor is dischargedfrom a headbox onto a wire so that the stock liquor, while beingtransferred on the wire, is dewatered by a dewatering equipment and isfurther dewatered by a suction box, characterized in being constructedsuch that a forming roll, wound with a felt, is arranged movably up anddown above the wire near the headbox and, when a thin paper is to beformed, the forming roll is moved down so that a nip of the stock liquoris formed between the wire and the felt.

[0048] According to the paper forming device of the present inventionconstructed as mentioned above, when a thin paper is to be formed, theforming roll is moved down to thereby press down the wire. In thisstate, forming of the wet sheet is done. In this state, the stock liquordischarged from the headbox onto the wire is immediately nipped betweenthe wire and the felt to receive a centrifugal force and a compressionforce due to the tension of the wire. Hence, the most part of the waterin the stock liquor is dewatered and the wet sheet is rapidly formed.

[0049] Thus, according to the paper forming device of the presentinvention, when a thin paper is to be formed, by moving down the formingroll, the stock liquor discharged from the headbox is immediately nippedbetween the wire and the felt. Thereby, scattering or the like of thestock liquor on the wire is suppressed and a high velocity forming ofthe thin paper becomes possible. Also, a shear force is generated in thestock liquor and fibers are oriented in the running direction of thewire. Thereby, a soft thin paper can be easily formed. Thus, accordingto the device of the present invention, a high velocity forming of thethin paper becomes possible.

[0050] On the other hand, when a thick paper is to be formed, theforming roll is moved up and the wet sheet is formed by the sameconstruction as a prior art device.

[0051] In the paper forming device of the present invention that ispreferably constructed such that, when the forming roll is moved down tothereby press down the wire, the headbox and the forming board arrangedunder the wire are inclined in the same direction as the runningdirection of the wire so pressed down, the position relation between thewire running direction and the headbox and/or the forming board can bemaintained.

[0052] Also, the paper forming device of the present invention can beconstructed such that a wire roll is arranged upwardly movably under thewire downstream of the forming roll and, when the wire roll is moved upto thereby lift up the wire, the forming roll is moved down so that thehorizontal running direction of the wire near the headbox is maintained.Then, even when the forming roll is moved down, the horizontal runningdirection of the wire between the breast roll and the forming roll canbe maintained and, in forming not only a thick paper but also a thinpaper, displacement of the headbox and the forming board becomesunnecessary.

What is claimed is:
 1. A paper forming device of a paper machine inwhich stock liquor is discharged from a headbox onto a wire so that saidstock liquor, while being transferred on said wire, is dewatered by adewatering equipment and is further dewatered by a suction box,constructed such that a forming roll, wound with a felt, is arrangedmovably up and down above said wire near said headbox and, when a thinpaper is to be formed, said forming roll is moved down so that a nip ofsaid stock liquor is formed between said wire and said felt.
 2. A paperforming device of a paper machine as claimed in claim 1, constructedsuch that, when said forming roll is moved down, said wire is presseddown by said forming roll and said headbox and a forming board, arrangedunder said wire, are inclined in the same direction as a runningdirection of said wire.
 3. A paper forming device of a paper machine asclaimed in claim 1, constructed such that a wire roll is arrangedupwardly movably under said wire downstream of said forming roll and,when said wire roll is moved up to thereby lift up said wire, saidforming roll is moved down so that a horizontal running direction ofsaid wire near said headbox is maintained.